Re: so35

Bob and fellow sat ops,
You have made some good points Bob, and your prowess as the father of
APRS is well known and appreciated. However, apparently you don't
operate ALL of the LEO birds. Your post tells the tale.
Bob Bruninga wrote:
> Having completed a weeks worth of HT testing via MIR using rubber ducks
> and being 100% successful, and having done the link budget, there is
> absolutely no need for any power over 5 watts on ANY OF THE BIRDS except
> AO-10. The problem is congeston. So people add power to 50 watts
> to override the QRM and then add a 160 watt linear and an OSCAR array
> to make sure they can step on all the 50 watt stations too.
Some do. Most don't. Try working RS-15 with 5 watts Bob. Your
testing on MIR proves what any of us able to work ALL the birds will
tell you: MIR is the easiest "bird" to work. Since it is not spin
stabilized, the antennas are always pointed at an optimum orientation to
the earth. I can hear MIR with an ancient Bearcat scanner sitting atop
my station, with a telescoping antenna. I can't hear FO-20, FO-29,
RS-15, AO-27 or any other bird with this setup.
> In my opinion, the uplink budget should be calculated for all birds and
> published. All stations must be encouraged to use only that power
> (ERP) for routine operations. This assures two things:
Good point. I would like to be on that panel. There is an article on
the AMSAT site that discusses the link budgets for some birds.
Experienced users will most likely disagree with part of you assessment
however.
> Unlike terrestrial comms, if 5 watts will do it, then 5 watts will do it
> always.
Not ALWAYS. Again, perhaps your experience on MIR would lead you to
believe this is true, but with over 2,000 satellite loggings, mostly on
the LEOs, I can tell you otherwise.
> The AO-10 OSCAR arrays are needed for the NON LEO birds, but they are
> great overkill on all the LEO's.
You can work the LEOs with a pair of eggbeaters. Can you work them
well? No. Can you work them to the horizon? No. Can you change
polarity on the uplink or downlink to compensate for changing polarity
sense? No.
There is a large community of sat ops out here who would disagree with
you that their carefully built Oscar stations are overkill. Please read
my previous posts about the need for a fleet of easy sats before you
think I am a sat op elitist. There should be more easy sats for the
masses. But, the fact is, the present fleet of satellites DOES require
a directional, steerable array WITH switchable polarity sense to work
all the LEOS reliably.
Many factors contribute to the need for all those adjustments on the
LEOS. I can usually tell you when there is band enhancement on 2
meters, without even tuning to the SSB call frequency. How? By working
FO-20, and sensing how my uplink signal is reaching the bird. When
there is some band enhancement, it eats part, if not most of my signal
on the way up. Other times, tropospheric ducting will capture my signal
and port it away from the bird. Other times, I can turn my power output
down to 1 watt and work the bird with no problem. Some passes over the
polar regions will cause the polarity to change mid sentence; Faraday
rotation? How about anomalous doppler?
All of this operation requires constant "testing" of the polarization
sense best used on both the uplink and downlink. It is nice to have the
ability to work the birds under most circumstances. You don't have to
have all those capabilities to work the birds 50% of the time, but to
work the birds 100% of the time, you bet you do.
Many of us regulars on the LEOS go out of our way to open the door for
new operators, and routinely ask partners in QSO to take a pause for
another station coming on frequency. Believe me, there are many
operators out there working with marginal equipment, and it's the well
equipped stations who give them the chance to work the bird.
Regularly, the AGC circuitry is pumped on the FO birds, making it
difficult to carry on a QSO with minimum power. The culprit, if not
unknowing terrestrial FM stations, is usually an operator with a poor
downlink antenna, overcompensating on the uplink to hear their signal.
Generally, here is where the 160 watt amps enter into play, not by the
"Oscar equipped" stations to which you refer.
When FG5GI in Guadeloupe gets on the LEOs with his vertical antennas,
it's not the guys with the eggbeaters or Jpoles who hear him first, it's
the fellows with the gain antennas who first grab him and pass the QSO
around.
>
> Not only that, but it feeds the mentality that you have to have a BIG
> OSCAR station to work the satellites and it keeps many newbee's from
> joining us, when in fact, the OSCAR array is of diminising value on any
> satellite other than AO-10.
Again, you don't need a BIG station to work the LEOs marginally 50% of
the time, but many of us are full time satellite operators who keep
regular schedules with each other. Most of us didn't go out and buy a
turnkey system, but spend a great deal of time and effort assembling and
keeping our stations in prime.
I would gladly share the design for my 35' fold over tower. It's made
of 4x4s and a 22 foot length of schedule 40 galvanized 2" pipe. It
works great and cost me around $100. There are many plans for home brew
cross-polorized antennas out there. Ramsey sells an $18.00 preamplifier
kit. A pair of those work quite well and are very helpful for increasing
the satellite time you can enjoy on the LEOs. Hard line can be
scrounged from a local cable crew. It doesn't HAVE to take big bucks to
have a big station.
I don't mean to be be nasty or heartless in this missive Bob. Limited
experience on MIR and AO-27 does not qualify you to make some of
statements you have in your post. Having a V8 engine in a Trans Am
doesn't mean you have to break the speed limits to enjoy the car. You
can lope along with the other cars at the normal speed, but, you have
that reserve capability under your hood to take emergency action if
needed.
This analogy applies to the well equipped Oscar operator. Go visit one
of those stations and watch how they work the controls like a well oiled
muscle car. Being able to work all the birds all the time is an asset
to the amateur satellite community, and the skills required are hard won
abilities any world class operator should be proud to possess.
Fortunately there is room for all of us, and all of us have our place.
Some fishermen opt for cane poles. Others hone their fly fishing
skills. To each their own, as long as it isn't to the detriment of
other's enjoyment.
73, Mike in Fort Myers, FL
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^ --- * -----------------.OOOo--oo--oOOO.------------------- *
||| | | * Mike Gilchrist - KF4FDJ ..... AMSAT Area Coordinator *
|X| | | * P.O. Box 763 ................ AMSAT member #31884 *
[X]~~~|k| * Fort Myers, FL 33902 ....... ARRL member #1781549 *
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| | |4| * kf4fdj@amsat.org ............................ EL96ap *
| P | |f| * I.S. Professional ..... CNA .... Computer Consultant *
| 3 |=|d| * AO10, AO27, FO20, FO29, RS13, RS15, MIR, E Layer *
| D | |j| * Bringing Oscar demos to the Lee County Schools. *
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